Bore safety device for time fuses



. NQV. 9, 1948. R. H, WHITEHEAD 2,453,682

' BORE SAFETY imvmEs FOR TIMEFUSES Filed June 20, 1939 H" v INVENTOR ATTORNE'Y Patented Nov. 9, 1948 BORE SAFETY DEVICE FOR TIIVE FUSES Richard H. Whitehead, New Haven, Conn, as-

signor, by mesne assignments, to the United States ofAmerica Application June 20, 1939, Serial No. 280,071

2 Claims. (Cl. 102-84) This invention relates to a bore safety device for time fuses to prevent the possibility of the fuses from being detonated prior to their insertion in the gun and until they have been expelled from the gun.

Time fuses, as now manufactured, comprise generally a specialized type of clock train which is started in action at the time of firing and which have a time train adapted to be fired as soon as the clock mechanism releases the firing pin. The mechanism which restrains a movement of the firing pin until released by the timing mechanism is delicate, relative to the severe forces to which it is subjected, and on this account, particularly when manufactured under quantity production methods, rough handling or slight inaccuracies of manufacture make it possible that the firing pin shall be discharged prematurely as the forces from set back at time of firing are tremendous and might cause a premature firing.

It is an object of this invention to provide a mechanism within such a fuse which will absolutely prevent the detonation of the fuse until the fuse has actually left the gun.

The invention accordingly comprises an article of manufacture possessing the features, properties and. the relation of elements which will be exemplified in the article hereinafter described a and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description, taken in connection with the accompanying drawing, in which:

Fig. l is a plan View of my improved mechanism as applied to a fuse. This figure being a section on the line l! of Figure 2 through the fuse itself.

Fig. 2 is a side elevation of the fuse, parts being broken away to show the relationship of the invention in the fuse.

The invention being applicable to substantially any type of modern time fuse having a firing pin released by the timing mechanism; I have not deemed it necessary to include a description of Iany particular type of fuse construction. Sumcient to say that it comprises generally a frame Ill which may be composed of a plurality of superposed plates, if desired, and carrying a time train, not shown, driven by centrifugal weights l I in response to the rotation of the fuse due to the rifiing of the gun or by other driving means such as wound springs.

The time train is provided with some sort of setting mechanism not described, in accordance 2 with which after a predetermined time the fuse is detonated. This is accomplished as follows:

Mounted in the frame I0 is a firing pin I2 urged downwardly by a compressed helical spring It so that when unimpeded it may be forced to its lowermost position as shown in dotted lines at M to detonate the primer. The firing pin' I2 is, however, provided with a shoulder l5 which is engaged by a lever member 16, the action of which is controlled by the time train. The connections between the time train and the lever l6 are not here described in detail because they form no part of this invention, it being sufiicient to say that the firing pin is held in its cocked position by the lever l6 until thelever I6 is released or withdrawn by the time train. In general it is customary that the lever 16 shall be of such a nature that it is thrown out of position from beneath the shoulder 15 by centrifugal force and that it is held in position by the time train so that the force for throwing it out is dependent upon the rotation of the shell. cases, particularly where the underside of the shoulder I5 is convex, the force of the spring itself may tend to throw the lever out even while the shell is stationary.

The foregoing parts comprise a part of the structure of a standard fuse.

In accordance with this invention there is provided transverse to the pathway of the firing pin a groove H. In practical construction this may be provided by dividing the frame It] into two portions by a separate plate l8 out out as shown at l9 in Figure 1 to provide the clearance desired. Within this clearance there is mounted upon a pin 20 a dog 2! which is movable about the pin 2|] from a position across the pathway of the firing pin i2, as shown in solid lines in Figure 1, to a position free from the pathway of the firing pin l2 as shown in dotted lines in Figure 1, being across the pathway in the inner position and away from the pathway in its outer position so that the normal centrifugal force due to the rotation of the shell in response to the rifling of the gun throws the dog to its outer position so that it no longer obstructs the movement of the firing pin.

A soft spring 22 bears against the dog 2| normally to assist in holding it in its inner position 'during the normal handling of the fuse, but the Nevertheless, in some aaeaesz propulsive charge of a large gun are not well un- 1 derstood and any statement based-upon them is necessarily, therefore, clouded by that lack'of definite knowledge. example, for naval operations, intended for use in five inch guns and in such a gun that shell during its travel through the bore of the-gun.

starts from rest and is brought to a speed of over 12,000 revolutions a minute in perhaps less than .01 of a second. During this period, acceleration forces are very strong and may be in excess of the centrifugal forces and this fact is utilized to help keep the bore safety closed. As will be seen fromFigure 1, the attempt rapidly to accelerate the structure of Figure 1 ins, counterclockwise. direction will tend to make the pin 20 drag; the-dog 2|; directly behind 'it and this is the. period when the maximum protection is required while-the. projectile is in the bore of the gun.. Asasoon, however, as the rotation of the shell becomes-more uniform inits rate and at tainsits. maximum velocity and the acceleration fallsoff the centrifugal forces resulting from the rotational-velocity become dominant and .these in turn are of great. dimension because of the high'speed of rotation... At thisitime the dog 2| is thrown violently outward out,of the path of the firing pin. g

From this construction two facts will be noted. (1) that the dog" 2| is'never in contact with the firing pin [2 unless there has been a premature release of the firing pin by a failure of the timing mechanism orby the set back forces. Thus there is no friction between the dog 25 and its cooperatingparts: which has any bearing upon the'norma'l operationof: the time fuse. It will also be noted that the dog 2| moves in substantial contactiwith'the plates below and 'if itis struck by the firing pin it has the full support of that plate: to resistthemo-vement of-the firing pin. The force of the firingpin is; however, considerable and rifthedogi-is' irritheway it tends to imbed itself in. the surface of -the-dog,- thus if theepin ,-be.--premature1yreleased .by the firing mechanismnthe dog-itself'is held inposition-by the firing pinto,- preventpremature explosion.-

It .willthus be seen--that=this--device, so long asthe-dogQ-L is across the path. of the-firingpin, absolutely. prevents any. detonation by the firing pinrnomatterwhatthe failure of. the timingmeche anism may. be and that the .dog 21.. during the rest is held in this obstructive position by the spring22, 'while in the bore of the gun there is brought into-play the additional factor of the acceleration ofthe shell to'prevent, the movement of' the dog 2! and this: is not overcome until after theshellleaves thezgun;

Since certain changes may be made in the aboveconstruction' and different embodiments of the invention couldv be made without departing These time fuses, are, for

from the scope. thereof,itisintendedthat all terpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention what I claim as new and desire to secure by Letters Patent 1. In a time fuse having a timing mechanism, a firing pin mounted for movement parallel to its'own longitudinal axis, means releasable by said timing mechanism to retain said pin in cocked position, means to move said pin when so released,- a plate disposed transversely to said pin and apertured for passage thereof, and a dog pivoted atone end disposed to cover said aperture when in unarmed position and movable by centrifugal force to uncover said aperture, the pivotal point of said dog lying angularly in advance ofnrsaid aperture. in the direction of rotation of said fusewhen in flight in a projectile,.the centerwof'gyration .of; said dog being so positioned withrespect to the pivotal point of the dog that centrifugal force does not move said dog until acceleration. has ceased, a leaf spring fixed at oneendrand having a free.- end bearing against the edgesof said. dog more remote from the center ofsaiddevice to: oppose fortuitous movement of said. dog, there being innsaid edge of'the dog, a cut-out portion-in which-said .free end. of the springengages when said doghas been moved to uncover said aperture-to lock said dogafter beingnioved;

2.l;In a time fuse-havinga timing mechanism, a firing-"pinmounted-for movement parallel to itsrsown-longitudinal.axis, means releasable by saidtiming mechanismv to retain said pin in cockedvpositiom,means to move said pin whenso released, a plate disposed transversely to said pin and-apertured-for passage thereof, and a dog: pivoted-atone enddisposed 'to-cover said larly'in-advance of said aperture in the direction.

of rotation of saidfuse: when inflight in a projectile,the centerof. gyration of said dog being.

so positioned with respect to the pivotal point of the dog that centrifugal force does, not move said dogv until acceleration hasrceased, yieldable means bearing againstthat edge of the-dog more remote from .thecenter of said device to oppose fortuitousmovement of thedog, said edge having a shoulder to engage said yieldable meansv whensaid dog-,hasbeen moved to. uncover said aperture to locksaid. dog after being moved...

RICHARD H, WHITEHEAD.

REFERENCES CITED The following references are of-record in the,-

file of" this patent} UNITED STATES PATENTS Number 1 Name Date,

797,;469: Stitcht Aug. '15, 1905 1,301,760 Stone et a1 Apr. 22,'1919-- 1,532,368 Bold, Apr. 7, 1925 FOREIGN PATENTS Number Country Date.

35,441 j France Dec. 28, 1927 

